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Subaru Impreza History
The Birth of a Legend
The first STi was launched in January of 1994 and was a response to Mitsubishi's Lancer GSR Evolution. The Lancer GSR was quicker than the standard Impreza so WRX's were taken to Subaru Technica International to be fitted with a tuned and blueprinted engine. This STi came with forged pistons, lightweight valve adjuster system, polished intake ports, a revised TD05H turbo and a remapped ECU. The spec was the same for both the Saloon and Estates with the engine producing 250hp @ 6500rpm and 288lbs/ft of torque @ 3500rpm.
Extras to come with the STi included Intercooler watersprayer, uprated intercooler ducting, a larger bore Fujitsubo exhaust system, loads of pink STI badges, an STi chassis plate on the offside front suspension tower, front strut brace, uprated brake pads, stiffer STi springs and dampers and the now familiar high level rear boot spoiler.
Inside was red stitched Nardi steering wheel, STi gearknob, STi dials and STi semi bucket seats. The STi was also available with a large range of options including a limited slip diff for the rear axle. The Impreza STi was available in Red, Silver and Black with the Version 1 STi using the same gearbox as the WRX.
The Type RA (Race Altered) STi was launched in November of '94, it was similar to the STi but was lighter, more powerful, having 275hp@6500rpm and 235lbs/ft@4000rpm. The Type RA also had a diver controlled centre differential (DCCD) with a rear limited slip differential which allowed between 50 and 65 percent of power to the rear wheels via a 5 step adjustment. The Type RA also came with closer gear ratios which made acceleration quicker, WRX style front foglamp covers, 16inch gold alloy wheels, silver and black strut brace, rally style roof vent, a faster steering rack and Type RA badging on the boot lid.
In August 1995 the C Spec STi Version 2 series was released. This Impreza was similar to the original STi but power was hiked to 275hp@6500rpm and 235lbs/ft@4000rpm. These cars came with the red induction manifold but the RA did without. This time the estate STi came with less power, 260hp and 227lbs/ft. Also released was the 555 WRX STi saloons and Estates which came which a deluge of stickers, a roof vent. The V Limited edition was released at approximately the same time, this was based on the Type RA but cam without stickers. A white only Type RA was released after, this had a polished exhaust system and minor internal changes.
Subaru brought out a heavily updated STi (D Series) Version 3 at the end of 1996 which reached the Japanese market ceiling of 280hp@6500rpm. The intercooler on this car was mounted flat as opposed to the slightly tilted position on earlier versions. The Type RA now gained the red inlet manifold and a carbon fibre strut brace. The open decked engine boasted lighter forged pistons, molybdenum coated valves, a metal head gasket, a better radiator an improved single bore exhaust system, stronger clutch and an STi quick shifter.
A new face appeared in January 1997 in the form of a 2 door STi Type R. It had a stiffer 2 door body shell, a front lip spoiler, side skirts, a deeper rear valance plus Type R badging and tinted rear windows. It also had an even closer Group N gear ratios, manual control of the intercooler water sprayer, air conditioning, folding mirrors and blue faced gauges. This model was available in Feather White, Sonic Blue Mica or Chase Yellow. Today the STi Type R is one of the most sought after Imprezas today.
The E Series STi version 4 was released in September 1997 with the main changes being in the interior. This consisted of a new dashboard, revised instrument clusters and a central speedometer. Power remained at the maximum allowed, 280hp but torque was raised to 260lbs/ft@4000rpm.
The E series also had one of not the most desirable Imprezas ever. In September March 1998 the 22B (WRX STi Type R 22B) was released with a run of only 424 vehicles of which 70 were brought to the UK with only 16 of these being officially imported and badged as 22B Type UK. Although the 22B was based on the Type R bodyshell it was redesigned by Mclaren F1 designer Peter Stevens. Stevens brought in WRC bonnet vents, an adjustable boot spoiler, bigger wheel arches, a wider track (20mm front, 40mm rear) unique interior and alloy wheels, better brakes, suspension, clutch, steering rack and turbocharger. But most importantly the engine was bored out to 2.2 litres and produced 280hp and almost all of its 265lbs/ft at a much lower 2800rpm.
September 1998 saw the release of the new F Series Version 5 which had a revised front spoiler, massive rear spoiler, STi fog lamp covers and engine revisions but power and torque remained the same.
The final version of the Classic Shape Impreza came in September 1999 with the G series STi engine version 4. This had only minor changes from the previous car.
The classic Impreza finished off with the S201 in April 2000. This Impreza was a limited run of 300 examples and was based on the STi RA Version 6 cars. It had a wild looking body kit and a 300hp engine.
Technical
All STi saloons, estates and coupes were based on the similar body shell to the WRX except for the 22B which had a bespoke shell.
Each Impreza has an EJ20 engine as its heart. This 1994cc 4 cylinder engine had 16valves, a quad cam with horizontally opposed cylinders. Each turbo was fitted with a top mounted air to air intercooler and can be found with various Mitsubishi TD series or IHI VF series turbos attached. From the Version 3 onwards mechanical as opposed to hydraulic lifters were used and molybdenum coated pistons. This engine has a 92mm bore and 75mm stroke and had 8.00:1, 8:5,1 or 9.0:1